After Debian 5.0 Lenny to Debian 6.0 Squeeze upgrade I also
had to manually activate volume groups (vgchange -ay) in every boot.
The patch lvm2_wait-lvm.patch resolved this issue.
Kernel is linux-image-2.6.32-5-amd64 2.6.32-30 and lmv2 is 2.02.66-5.
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Mikko Lehto
Setera